1. Field of Invention
This invention relates to devices that are particularly useful in the manufacture of vehicle tries and relates, more particularly, to apparatus defining an inner circumference suitable to serve as a circular surface to grasp the outer circumference of a circular, tubular or round object, usually for purposes of transferring of the grasped object between first and second locations. More specifically, this invention relates to an improved transfer ring, useful in the manufacture of vehicle tires.
The manufacture of a vehicle tire commonly includes the steps of forming a tire, carcass, forming a toroidal belt and tread portion of the tire separately of the carcass, and thereafter marrying the belt and tread portion of the tire to the carcass to form a “green” tire. The green tire is thereafter treated to form the tread and various other features of the tire. Other supplementary steps, such as stitching may be performed during the course of or following one or more of the aforementioned steps.
2. Description of the Related Art
As seen in FIG. 1, formation of a belt and tread portion of the tire is accomplished on a belt and tread drum 12 such drum has an outer cylindrical surface, or circumference, about which one or more layers of the tire belt material (comprising for example, reinforcement cords embedded in a polymeric binder) are laid to define the belt and tread package. The circumference of such drum is preferably capable of expanding and contracting to, for example, accommodate the removal from such drum of a completed belt and tread package which is essentially nonexpandable radially, but which is flexible to the extent that when unsupported, the toroidal package will sag under the influence of gravity. Also, desirably, the adjustable circumference of the belt and tread drum enables a single drum to be used to form belt and tread packages of alternative diameters.
In the manufacture of vehicle tires, the drum upon which a carcass is formed is somewhat similar to the drum upon which the belt and tread package is formed. Subsequent to the formation of the carcass such carcass commonly is transferred to an expansion drum 14 and while the carcass remains on its forming drum, it is overlaid with a toroidal belt and tread “package”.
In some instances, after the carcass has been formed, it may be transferred to a second stage drum, employing a transfer ring, and held thereon while a belt and tread package is transferred from the belt and tread drum onto the outer circumference of the carcass, also employing a transfer ring. Thereafter, the belt and tread package is married to the carcass.
Desirably a transfer ring as employed in the vehicle tire manufacturing industry, incorporates a maximum range of adjustability of diameter of the transfer ring such that the transfer ring can be used in the manufacture of a relatively large range of vehicle tire sizes (diameters). In order for the individual shoes of a transfer ring to move radially outward, the mechanism for mounting each of the shoes includes a hinge connection of the shoe to the mechanism which moves the shoe generally radial, inwardly and outwardly. This hinged connection permits the shoe to rotate freely about the hinge connection. In applicant's U.S. Pat. No. 5,635,016, rotation of the sections of multi-sectional arcuate segment (i.e. shoe) is controlled by guide plates attached to the sections of adjacent shoes and which interact with pin means on the sections of adjacent shoes to aid in maintaining the collective circular attitude of the sections of the several shoes as the diameter of the circle collectively defined by the shoes is increased or decreased in diameter. The fabrication, installation and maintenance of this type of interconnection of the adjacent shoes of the transfer ring or drum, however, are time consuming and expensive.
Further, applicant's U.S. Pat. No. 5,709,768, there is disclosed a transfer ring wherein the plurality of shoes are mounted on the outboard ends of respective arms, whose respective inboard ends are rotatably mounted on a fixedly mounted ring. The inboard end of each arm further includes a rigid bracket element which in turn, is included in a “train” of such bracket elements. The geometry and mounting aspects of these bracket elements are chosen such that upon the application of a linear force to the train of bracket elements, the arms are caused to rotate about their inboard mountings with resultant accurate movement of the outboard ends of the arms (and the shoe attached thereto) inwardly and outwardly of the longitudinal centerline of the transfer ring. Among other things, this device is limited as to the directionality of the path of the inward and outward movement of the shoes on the arms, and lacks capability for minimization of the force transferred from the shoes to the power source associated with the device.